A reverse osmosis (RO) water purifier (hereafter referred to as a water purifier) used at home performs water clarifying through 3 filters, including a preprocessing filter membrane, an activated carbon filter and a micron filter membrane. Then purified water is produced by the water purifier and stored into a water reservoir disposed independently.
Since these three water clarifying process filters, the water purifier and the water reservoir are separated from each other, this equipment has a deficiency of occupying too much space to install under a water tank.